It is desirable to remove manganese from rice protein because the inherent level of manganese in rice alone may be greater than the total desired in a nutritional product, such as a liquid nutritional formula for infants.
Phytic acid, also known as inositol hexaphosphate, is a myo-inositol molecule in which all the hydroxy groups have been replaced by phosphate groups as shown in FIG. 1. Phytic acid is the source of up to 85% of the total phosphorus in many cereals and legumes. Phytate is the salts of phytic acid. Phytic acid is believed to reduce the bioavailability of essential minerals by forming complexes with them. Also, it may influence the functional and nutritional value of proteins.
Aluminum is known to form complexes with phosphates. Classically, aluminum sulfate, commonly known as alum, has been used to remove inorganic phosphates in water purification processes. Alumina (aluminum oxide, Al.sub.2 O.sub.3) is insoluble in water, practically insoluble in organic solvents, and only slightly soluble in aqueous alkaline solutions with the formation of hydroxides. The ability of the aluminum portion of the aluminum oxide to attach to the phosphate portion of phytate was the theoretical and practical basis for its initial experimental use in the reduction of phytate in proteins.